Production dip and monthly average: A TV factory produces on average 60 sets/day for the first 25 days of a month. Illness lowers output over the last 5 days so that the monthly average becomes 58. What is the average production per day during the last 5 days?

Introduction / Context:
Block averages (first 25 days, last 5 days) can be combined via totals to reach the monthly average. Subtract the known block to get the unknown block's total and divide by its length.

Given Data / Assumptions:

• First 25 days average = 60 ⇒ total = 1500.
• Monthly average = 58 across 30 days ⇒ total = 1740.
• Need average over last 5 days.

Concept / Approach:
Last 5 days total = monthly total − first 25 days total. Then divide by 5.

Step-by-Step Solution:

Verification / Alternative check:
Weighted average check: (1500 + 240)/30 = 1740/30 = 58. Works.

Why Other Options Are Wrong:

• 45 or 52: Would yield monthly totals different from 1740.
• 58: That is the monthly average, not the last 5-day average after a dip.

Common Pitfalls:
Averaging 60 and 58 directly instead of using totals and correct day counts.

Final Answer: